Hydraulic power transmission



A118' 4 1942- l.. F. MEUNIER HYDRAULIC TRANSMISSION Dec. 26. 1946- 4 Sheets-Sheet l INVENTOR F M54/ A//FA MIM All@ 4, 1942- L. F. MEUNIER 2,292,146

HYDRAULIC POWER TRANSMISSION 4 Sheets-Sheet 2 Filed Dec. 26, 1940 I INVENTOR Ea/v E MAUN/Ef?.

ATTORNEY Aug. 4, 1942. 1 F. MEUNIER 2,292,146

HYDRAULIC POWER TRANSMISSION Filed Dec. 26, 194C 4 Sheets-Sheet 5 INVENTOR t0/y F. M5L/Nase BY r ' ATTORNEY 4 Sheets-Sheet 4 Aug. 4, 1942.

L. F. MEUNIER HYDRAULIC POWER TRANSMISSION4 Filed Dec. 26, 1946 @cuando HYDRAULIC POWER TRANSMISSION Leon F. Meunier, Cleveland, Ohio, assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application December 26, 1940, Serial No. 371,671

17 Claims.

This invention relates to hydraulic means for transmitting a rotational impulse of predetermined intensity, and relates more particularly to transmission means of this kind capable of embodiment in rotary tools for use in nut running, screw driving, threading, tapping and like operations.

While broadly applicable to any tool of this general class the invention has especial value in power driven nut running tools, since it provides a means for setting each of a series of nuts to the same predetermined degree of tightness.

One object of the invention is to embody in a nut running or like tool an integrally formed hydraulic transmission including a fluid reservoir, a pump for circulating fluid and a rotary motor operated by the circulation of fluid.

Another object of the invention is to limit the pressure applied through the hydraulic circuit to the motor to a rotational impulse of an intensity less than the maximum intensity which the pump is capable of developing.

Another object is to enable the intensity of the rotational impulse delivered to the motor to be varied at the will of the operator.

A further object is to prevent the application of repeated impulses to the motor during a single nut running operation.

In carrying out these objects relating to the control of hydraulic pressure, there has been provided a control element settabl'e to first and second control positions to render the transmission means effective and ineffective, an adjustable pressure responsive pilot valve within the hydraulic circuit for controlling movement of the control element from rst to second position, and means arranged to be operated by pressure of the tool against the work for setting the control element from second to first position.

Other objects and structural details of the invention will be apparent from the following description when read in conjunction with the accompanying drawings, wherein:

Fig. 1 is a view in longitudinal section of the front end of a nut running tool embodying the mechanism of the present invention, this View being taken along the irregular line I-I of Fig. 4;

Fig. 2 is a View similar to Fig. 1, showing the tool in the act of running up a nut;

Fig. 3 is a view similar to Fig. 2, showing the nut in seated position and the hydraulic transmission automatically disabled;

Figs. 4, 5 and 6 are cross sectional views of the 55 tool, taken substantially along the respective lines 4 4, 5 5 and 6-6 of Fig. 1; and

Fig. 7 is a view in cross section, taken substantially along the line 'I-I of Fig. 2.

The invention is thus concerned primarily with a novel transmission means intermediate rotary driving and driven elements. For convenience of illustration, therefore, the drawings are limited to a showing of driving and driven shafts, in association with the present transmission, disclosed as embodied in a nut running tool of otherwise conventional construction. Such a modication of the usual tool serves to produce a front end construction of the kind shown in Figs. 1, 2 and 3 adapted for use in either portable handheld tools or in stationary pedestal-mounted machines.

Referring to Figs. 1, 2 and 3, the driving shaft is indicated at I0 and the driven shaft at II. The shafts are axially aligned and are supported in a frame assembly comprised of a plurality of interconnected pieces I2, I3, I4 and I5 secured to the front of the main tool body I6. The shaft ID extends rearwardly through the main frame IB and may be geared or otherwise connected tov a prime mover such as an electricq or compressed air motor. The adjacent ends of the shafts IU and II terminate within a casing 20 and are mounted in respective ball bearings I1 and IB. Additional anti-friction bearings I9 and 2l are provided for the shaft I0 rearwardly of the cas'- ing 20 while the front end of the shaft II is mounted in another ball bearing 22 in advance of the casing 20. As shown in Fig. 2, the outer or front end of the driven shaft II Iprojects into the recessed inner end 3D of a spindle 23 and has a splined connection therewith. Thus the two elements are caused to rotate as a unit but are permitted relative longitudinal movement. The outer end of the spindle 23 is formed with a recess shaped in correspondence with the polygonal shank of a working implement 24 adapted to be inserted therein. The implement 24 has a nut engaging socket 25 secured thereto and is held within the spindle 23 by a retainer assembly or chuck including a set of locking balls 2B supported within the spindle 23 in cooperative relation with an annular groove 2'I in the shank of the working implement. Thus, when the rotary motion of the drive shaft I0 is transmitted to the driven shaft II the spindle 23 and working implement 24 are carried with the driven shaft and the work of running up a nut performed in the manner indicated in Figs. 2 and 3. The spindle 23 is rotatably mounted in the front frame piece I5 and is limited in its forward longitudinal movement by the engagement of a flange 28 thereof with an internal boss on the frame. Rear- Ward movement of the spindle is limited by engagement of the front end of shaft I with the bottom of the recess 39.

The hydraulic transmission of the invention is comprised essentially of a gear assembly 23 (Figs. 1 and 4), driven by the shaft I0, for circulating fluid, and a gear assembly 3| (Figs. 1 and 5) operatively connected to the shaft I I and driven by such circulation of fluid. As will be seen from a comparison of Figs. 4 and 5, the assemblies 29 and 3| are similar structures of a well known kind in which a pair of intermeshed gear wheels is disposed in a confined hydraulic circuit and functions selectively as a pump, a motor or a brake. In the assembly 29 the lower one of the pair of gear wheels 32 is keyed to the shaft I While the upper wheel is loosely mounted in the frame in a manner not fully shown herein. In the assembly 3| the pair of gear wheels 33 is similarly mounted, but in this case the lower wheel is keyed to the shaft I I. The assembly 29 is thus positively driven by the shaft I0 and so adapted to function as a pump, while the assembly 3| being connected to the driven shaft II is adapted to function as a motor.

The hydraulic circuit includes a reservoir 34 (Figs. 1 3), formed in the frame casing I2, into which oil or other hydraulic fluid may be introduced'through a ller port 35. The reservoir communicates with a Vertical passageway 35 in frame piece I3 (see also Figs. 4 and 5) which opens into recesses or chambers 31 and 38 located respectively above and below the bearing casing 29. A passage 39 connects the chambers 31 and 38 to complete a circuit in which the oil may pass from the reservoir 34 to the chamber 31, through passage 39 to chamber 38 and through passageway 36 back to the reservoir. The gear pump 29 is disposed just inside the chamber 31 and when operated by a rotary motion of the shaft I Il draws oil from the passageway 33 and directs it in the manner indicated in Fig. 4 through the discharge side of the pump into the chamber 31. The gear motor 3| is axially aligned with the pump 29 and is arranged within the chamber 38. Oil discharged from the pump 29 flows through the passage 39 to the chamber 38 and is forced into the inlet side of the motor 3|. The pressure of the oil acting on the motor gears 33 effects a rotary movement of the gears, and, as indicated in Fig. 5, the oil is thereby carried through the motor to the passageway 36.

Thus, upon operation of the driving shaft I0 the pump 29 generates a flow of oil to the motor 3| which is thereby caused to rotate and drive the shaft and spindle 23. In a nut setting operation, the socket 25 is applied to the work in the manner shown in Fig. 2, and operation of the shaft I0 initiated to effect the circulation of oil through the hydraulic system. As the nut is advanced toward seated position it encounters but slight resistance to rotation and this part of the operation is performed at high speed and the oil pressure at the inlet side of the motor 3| is at a minimum intensity. As the nut reaches seated position, however, its resistance to rotation increases, and such resistance, as reflected in the motor 3|, serves to impede the ow of oil through the system. Since the pump 29 functions to deliver a constant volume of oil to the motor a restriction of the free flow of fluid results in a rise in pressure at the motor inlet,

which pressure is transmitted to the driven shaft II as a rotational impulse of increased power. If, when the nut is seated, the tool is still held applied to the work and the pump 29 is permitted to continue to operate, the oil pressure in the area intermediate the pump and the motor 3| will continue to rise and the nut will be further tightened in seated position. When the nut reaches a degree of tightness corresponding to the greatest pressure capabilities of the pump the resistance imposed upon the motor 3| will equal the oil pressure at the motor inlet and the pump will stall.

In the majority of nut running operations, however, it is desirable to set the nuts to a degree of tightness less than that obtained by a maximum elfort of the tool. As a part of the present invention, therefore, there is provided a control means, operating independently of the pump 29, for rendering the hydraulic transmission ineffective. This means takes the form of a fluid by-pass mechanism including a piston type valve 4| movable within a bushing 42 to open and closed positions with respect to a recess or passage 43 (see also Fig. 6) communicating with the passageway 35. The recess '.43 is formed in the frame piece I4, in advance of 'the motor 3i, and is connected to the motor'l inlet passage 39 through a pair of spaced ports 44 and 45 in the bushing 42. The valve 4| is formed with an annular shoulder 45 adapted in the closed position of the valve (Fig. 2) to occupy a position between the ports 44 and 45 and so prevent the ow of oil to the by-pass recess 43. In the open position of the valve (Figs. l and 3) the shoulder 45 is moved out of flow preventing position and the passage 39 and by-pass recess 443 are connected through the bushing 42. Thus, in the open position of the ley-pass valve 4| the hydraulic transmission is disabled since the oil delivered by the pump 29 to the motor inlet is permitted to make a substantially unrestricted circuit around the motor. shifted to open position while a nut is being tightened in seated position, the oil pressure at the motor inlet is immediately reduced to its normal level and the torsional pressure applied to the shaft II and spindle 23 is relaxed.

It is further desirable that the by-pass mech'- anism function automatically in order that a nut setting operation may be terminated when the nut reaches a predetermined degree of tightness, even though the pump 29 continues to circulate oil through the system. In the present tool automatic operation of the valve 4| is effected by fluid pressure and additional control means is provided for controlling the application of fluid to the valve. The additional control means includes a pressure responsive pilot valve 41 movable within a bushing 4S pressed in a longtudinal bore which opens at its upper end into the oil chamber 31. The valve 41 is arranged in the upper end of the bushing 48 and has a head portion 49 normally disposed between the open upper end of the bushing 43 and a passage 5I connecting the interior of bushing 48 to the interior of bushing 42 at a point above the by-pass valve 4 The upper end of the valve 41 is formed with a perforated annular flange which assists in guiding the valve. Communication between the chamber 31 and passage 5| is normally cut off and, when established by movement of the pilot valve downward to the position shown in Fig. 3 permits oil to pass to the upper end of valve 4I and force this valve downward to open posi- If the valve 4| is tion. The valve 41 is actuated by the pressure of the oil on the upper end thereof, and its movement to open position is resisted by a coil spring 52 interposed between the lower end of the valve and a set screw 53 adjustable from outside the frame piece I4. By means of the set screw 53 the force with which the spring 52 urges the valve 41 to closed position may be varied and the exact pressure necessary to operate the valve thereby determined. The pressure of the oil in the chamber 31 is the same as that at the motor inlet so that variations in the load or resistance imposed on the motor 3| are reflected by corresponding changes in the pressure of the oil above Valve 41. When the resistance of the motor causes the oil pressure to rise to a height suflicient to overcome the spring 52 valve 41 is forced to open position and oil at high pressure is directed through passage 5| against the upper end of valve 4|, thereby opening the by-pass recess 43 to relieve the pressure at the motor inlet.

It will thus be seen that the intensity of the rotational impulse delivered through the motor 3| to the nut is determined by the pressure of spring 52 which is controlled by the set screw 53. Each variation in the pressure with which pilot valve 41 is urged to closed position occasions a corresponding change in the peak pressure obtainable in the hydraulic transmission.

At the time the by-pass valve 4| is shifted to open position the nut has reached the proper determined degree of tightness, and it is unnecessary and undesirable that the tool should operate with a repeated action to deliver additional impulses to the nut. Therefore the bypass valve is not returned automatically to closed position but must be re-set manually to condition the tool for another nut running operation. According to a feature of the invention the re-setting means for the valve 4| is operated by pressing the tool against the work and is combined with a spring means which holds the valve yieldingly in closed position and is disabled by movement of the valve to open position. The by-pass valve is formed with a stem 4m (Fig. 1) extending forwardly through an oil seal 54 and lying within the frame piece l5 in cooperative relation with a pawl 55 pivotally supported on the outer end of a yoke 56. The separate arms of the yoke 56 embrace the spindle 23 and the inner end of the yoke is loosely mounted on a xed cross rod 51. The pawl 55 is pressed outward into engagement with the lower end of stem 4|a by a coil spring 58 so that if the yoke 55 is rocked upward or rearward about the rod 51 the valve 4| will be carried also upward from the open position of Fig. l to the closed position of Fig. 2. Upon actuation of the by-pass valve to open position, the pawl 55 is cammed inwardly by the advancing valve stern 4|a and is held in the disabled position of Fig. 3. Downward movement of the yoke 56 serves to restore the parts to the position shown in Fig. l. Referring particularly to Fig. 7, the yoke 56 is operatively connected to the spindle 23 and is rocked about the pivot rod 51 by relative longitudinal movement between the spindle and the tool body. Each arm of the yoke 56 carries a roller 59 so positioned as to lie between the previously mentioned annular iiange 28 on spindle 23 and a second flange 6I formed. on the upper end of the spindle. As shown in Fig. 2, a spring pressed plunger 62 is positioned within a recess in the front of shaft and presses against the bottom of spindle recess 30 to maintain the spindle normally in the position shown in Fig. 1, with the ange 28 resting on the internal frame boss. In applying the tool to the work the socket 25 is engaged with the nut to be set, and a relative movement between the spindle and tool body is eiected either by moving the work toward the tool or the tool toward the work. In either case such movement is accomplished against the force force of plunger 62 and serves to shift the yoke 56 and by-pass valve 4I to operating position. When the tool is Withdrawn from the work, plunger 62 acts to return the spindle 23 to the normal position of Fig. l, thereby rocking the yoke 56 forwardly to re-set the pawl 55 into engagement with the valve stem 4|a.

Immediately following movement of the bypass valve 4| to open position, the oil pressure in the chamber 31 is reduced sufficiently to permit the pilot valve 41 to be returned upward to closed position. In order that the actuating fluid previously admitted above the valve 4| may not thereby be trapped, an exhaust passage 63 is provided to which the oil may flow around a reduced portion 64 of the pilot valve. As shown in Fig. 3, the valve head 49 cuts off communication between passage 5| and exhaust passage 63 in the open position of the pilot valve. Oil iiovving into the exhaust passage may pass through a port 65 and around a reduced portion of the valve 4| to the by-pass recess 43. Additional ports 66 and 61 connect the exhaust passage 63 to respective chambers below the valves 4| and 41 in order that the pressure in these chambers may be kept at a normal level.

What is claimed is:

l. In a nut running or like tool having a work engaging spindle, the combination of a hydraulic power transmission including a pair of independently operablvegeanpunips, one adapted for positive operation to circulate fluid, and the other being driven by such circulation of nuid, a control element settable to rst and second positions to render the power transmission between said pumps elective and ineifective, and means arranged to be operated by pressure of the tool spindle against the work for setting said control element to its said rst position.

2. In a, nut running or like tool, the combination of a hydraulic power transmission` including a pair of independently operable gear'pumps, one adapted for positive operation to circulate fluid, and the other being driven by such circulation of fluid, a work engaging rotary spindle driven by the second mentioned of said pair of pumps and having a limited longitudinal movement reltively to the tool, a control element settable to first and second positions to render the power transmission between said pumps effective and ineffective, and means operable by said spindle during relative longitudinal movement thereof for moving said control element to its said first position.

3. In a nut running or like tool, the combination of a hydraulic power transmission including a pair of independently operable gear pumps, one adapted for positive operation to circulate fluid, and the other being driven by such circulation of fluid, a control element settable to iirst and second positions to render the power transmission between said pumps effective and ineffective, means for moving said control element to its said second position, and a pressure responsive pilot valve within said transmission for controlling the action of said last named means.

4. In a nut running or like tool having a work engaging spindle, the combination of a rotatable driving shaft, a rotatable driven shaft, transmission means including a hydraulic circuit intermediate said driving and driven shafts, a variably settable pressure control ele-ment within said hydraulic circuit having two positions of adjustment for opening and closing the circuit, and means operated by pressing the tool spindle against the work for moving said control element from one to another of its control positions.

5. In a nut running or like tool, the combination of a rotatable driving shaft, a rotatable driven shaft, transmission means including a hydraulic circuit intermediate said driving and ydriven shafts, a work engaging spindle op-eratively connected to said driven shaft and shiftable longitudinally thereof, a VariablVy/'settable pressure control element within said hydraulic circuit having two positions of adjustment for opening and closing the circuity and means operable by said spindle during a longitudinal shifting movement thereof for moving /said control element from one to another of its control positions.

6. In a nut running or like tool, the combination of a rotatable driving element, a rotatable driven element, transmission means including a hydraulicnpirpmuit-intermediate said driving and driven elements, a pump operatively connected to said driving element for circulating fluid through the circuit, and means for limiting the pressure applied through said circuit to said driven element to a single rotaipnadhimpulse of predetermined intensity, said means including a control element within said circuit and movable from a first to a second control position in response to the attainment of a predetermined pressure therein and movable from second to rst control position by manual means.

7. In a nut runningor like tool, the combination of' a rotatable driving element, a rotatable driven element, transmission means including a hydraulic circuit intermediate said driving and driven elements, a pump operatively connected to said driving element for criculating fluid through the circuit, and means for limiting the pressure applied through said cir/cuit to said driven element to a single rotatidnal impulse of predetermined intensity, said means including a pressure responsive pilot .valve within said circuit, and a settable control element movable from a first to a second position by pressure fluid within said circuit under the control of said pilot valve and movable from second to first position by manual means.

8. A hydraulic power transmission comprising a hydraulic circuit, a pu, p for circulating fluid through said circuit, a rotary motor -Within said circuit and operated 4by the circulation of fluid therethrough, said motor being arranged variably to restrict the flow"` of fluid through the circuit in response to variations in the load imposed thereon, a -by-pass for directing-fluid around said motor thereby to disable said motor, a valve controlling said by-pass and settable to open and closed positions with respect thereto, and a pressure responsive pilot valve within said hydraulic circuit controllingop'eration of said bypass control valve.

9. In a portable nut running or like tool, the

combination with rotatable driving and driven elements, of a hydraulic power transmission within the tool and comprising, a uid operated rotary motor operatively connected to said driven element, a fluid conducting passageway leading to said motor, means lcomprised in said motor for variably restricting the iiow of duid through said passageway as the load imposed on said motor is varied, a pump (operatively connected to said driving element for supplying a constant volume of iiuid to said passageway, and an adjustable A.pressure control means for limiting the pressure obtainable in said passageway to a predetermined peak less than the maximum pressure which the pump is capable of developing.

10. In a portable nut running or like tool, the combination with rotatable driving and driven elements, of a hydraulic power transmission Within the tool and comprising, a fluid operated rotary motor operatively connected to said driven element, a fluid conducting passageway leading to said motor, means comprised in said motor for variably restricting the flow of fiuid through said passageway as /he load imposed on said motor is varied, a p p operatively connected to said driving element for supplying a constant volume of fluid to said passageway, fluid pressure responsive means within said passageway, and means controlled by said fluid pressure responsive means for by-passing the fluid from said passageway around said motor.

ll. A nut running or like tool according to claim 10 characterized by means for vimparting to said fluid pressure responsive means a variable resistance to actuation.

12. In a nut running or like tool, the combination with rotatable driving and driven elements, of a hydraulic power transmission within the tool and comprising, a fluid reservoir, a fluid operated rotary motor operatively connected to said driven element, a pump operatively connected to said driving element for delivering uid from said reservoir to said motor to effect operation of said motor, and means independent of said pump for controlling the supply of fluid to said mot'or to limit the application of pressure through said motor to said driven element to a rotational impulse of an intensity less than the maximum intensity which the pump is capable of developing.

13. In a nut running or like tool, the combination of a hydraulic power transmission means including a iiuid operated rotary motor, a fluid conducting passageway leading to said motor, a pump for supplying fluid to said passageway to effect operation of said motor, a by-pass for directing fluid from said passageway around said motor, a valve controlling said by-pass and movable to op-en and closed positions with respect thereto, means for conducting fluid from said passageway to said valve in a direction to move said valve to open position, and means preventing the passage of fluid to said valve until a predetermined pressure is reached within said passageway.

14. In a nut running or like tool, the combination of a hydraulic power transmission means including a fluid operated rotary motor, a fluid conducting passageway leading to said motor, a pump for supplying iiuid to said passageway to effect operation of said motor, a by-pass for directing fluid from said passageway around said motor, a valve controlling said by-pass and movable to open and closed positions with respect thereto, means for moving said valve to open position, and a yielding means for holding said valve in closed position, said yielding means comprising a spring pressed pawl rendered ineffective by movement of said valve to open position.

15. In a nut running or like tool, the com-bination of a hydraulic power transmission including a fluid operated rotary motor, a pump for supplying iiuid to said motor to effect operation of said motor, means independent of said pump for controlling the supply of uid to said motor including a control element settable to first and second control positions, means for moving said control element from first to second position, a yielding means for holding said element in first position, said yielding means including a spring pressed pawl rendered ineffective by movement of said element to second position, and manually operable means movable to re-set said pawl in effective engagement with said control element and to move said element from second to first position.

16. A hydraulic power transmission comprising a hydraulic circuit, a pump for circulating fluid through said circuit, a rotary motor within said circuit and operated by the circulation of fluid therethrough, a by-pass for directing fluid around said motor thereby to disable said motor, a valve controlling said by-pass and settable to open and closed positions with respect thereto, means for conducting liuid from said circuit to said valve in a direction to move said valve to open position, a pressure responsive pilot valve within said circuit controlling the passage of fluid to said by-pass valve, and means for imparting a variable resistance to actuation to said pilot valve.

17. In a nut running or like tool having a longitudinally shiftable work engaging spindle, the combination of a hydraulic power transmission including a fluid operated rotary motor, a pump for supplying iiuid to said motor to elect operation thereof, means independent of said pump for controlling the supply of fluid to said motor including a control element settable to rst and second control positions, means for moving said control element from lirst to second position, a spring pressed pawl holding said element yieldingly in first position and rendered ineffective by movement of said element to second position, and means carrying said pawl and movable by said work engaging spindle in one direction to reset said pawl in eiective engagement with said control element and movable by said spindle in the opposite direction to move said element to rst position.

LEON F. MEUNIER. 

